Neutral Polymer Brushes

Because the neutral polymer brushes are unlikely to be very strongly stretched, the MWC approach usually provides in this case an accurate approximation. The situation is however different for the highly charged grafted polyelectrolytes, which are almost completely... 

A more detailed overview of theoretical studies on the structure of neutral polymer brushes is beyond the scope of this article and can be found in several review articles [12, 21, 22]. 

It is noted here that for the brush system obtained by adsorption of complex coacervate core micelles, as described in the previous section, the structure resembles very strongly the structure proposed for the zipper brush in Figure 7.8 (provided that the C3Ms spread their cores at the substrate surface). Both consist of a polyelectrolyte complex layer near the surface with, on top of that, a neutral polymer brush. However, the driving force for the for-mahon of the neutral brush is very different for the two systems. In the case of the zipper brush the electrostahc attraction between oppositely charged polyelectrolytes is the driving force in the micelle system it is the phase separation of the polyelectrolyte complex, which is much weaker. 

Figure 5 Qualitative plot of the polymer volume fraction vs. distance z from the substrate, for neutral polymer brushes and for polyelectrolyte (PE) brushes at low and high salt concentration, as indicated in the figure.

Theoretical Approaches to Neutral and Charged Polymer Brushes... 

Naji, A., Seidel, C. and Netz, R. R. Theoretical Approaches to Neutral and Charged Polymer Brushes. Vol. 198, pp. 149-183. 

Besides the analytical techniques, the theoretical description of polymer brushes allows a deeper understanding of the complex dynamic behavior of polymers on surfaces and is useful for future developments. Here, Roland Netz gives - also for the non-expert - a very helpful theoretical background on the theoretical approaches for the description of neutral and charged polymer brushes. 

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